Cute alert! Rare tiger cubs born at National Zoo

Video: The National Zoo in Washington, D.C., welcomed two additions to their family: baby tiger cubs born to a 4-year-old Sumatran tiger. NBC’s Tom Costello reports.

The Smithsonian National Zoo in Washington, D.C. is celebrating a pair of rare (and cute!) additions this week — two Sumatran tiger cubs.

The cubs were born on Monday, the zoo said Thursday, to a female Sumatran tiger, Damai, who mated with 12-year-old male Kavi. There are only 65 Sumatran tigers, which are listed as critically endangered, living in zoos in North America. Only 400 to 500 of the tigers, which weigh about 300 pounds, exist in the wild, according to the zoo.

The cubs, who will not be able to open their eyes for a few weeks, can be viewed live on the zoo’s webcams. They'll get their first medical checkup in four weeks and will go on display at the zoo in about four months.

Last month, after Damai mated with Kavi, the zoo staff performed an ultrasound through a wooden box with holes cut in the bottom, distracting her with raw beef slices to keep her still.

“Our hearts stopped when we put those cats together for the first time because there’s a chance that if we make a mistake and we make the wrong call, these animals will hurt each other, if not worse,’’ Craig Safoe, a great cats curator at the National Zoo, told TODAY Thursday. “Our little female has a little bit of spice to her, and she slapped around our boy quite a bit, but he turned out to be the coolest cat.”